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IV.—The Plutonic Rocks of Garabal Hill

Published online by Cambridge University Press:  01 May 2009

B. K. N. Wyllie  and
Alexander Scott
Alexander Scott
Affiliation:
Carnegie Research Scholars in the University of Glasgow.
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Extract

This complex of igneous rocks lies between Ardlui, at the head of Loch Lomond, and the head of Loch Fyne. In 1892 it was the subject of a fairly exhaustive paper by Teall & Dakyns, but in view of a number of new facts which we have discovered we venture to submit a re-examination of the problems connected with the complex. The mass is broken by a north-east fault. The country to the west of this fault is mainly porphyritic granite and tonalite; to the east there is tonalite and also more basic diorite and ultrabasic rocks. We shall concern ourselves mainly with the basic and ultrabasic groups, as they are somewhat unusual in the “Newer Plutonic Rocks of the Highlands”.

Type
Original Articles
Information
Geological Magazine , Volume 10 , Issue 11 , November 1913 , pp. 499 - 508
Copyright
Copyright © Cambridge University Press 1913

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References

page 499 note 1 “Plutonic Rocks of Garabal Hill and Meall Breac”: Quart. Journ. Geol. Soc., xlviii, pp. 104–21, 1892.Google Scholar

page 499 note 2 The sketch-map of Teall & Dakyns is reproduced in Hatch's Petrology (p. 303),Google Scholar but with the omission of all the peridotite areas we have mentioned, except the one we failed to find, while the positions of Garabal Hill and Garabal Cottage are interchanged.

page 499 note 3 Geology of Upper Strathspey, etc. (Mem. Geol. Surv. Scotland), 1913, p. 72.Google Scholar

page 501 note 1 The pleochroism of the hornblende is: X, light yellow; Y, dark brown; Z, reddish brown.

page 502 note 1 By annealing we mean reheating to a temperature which is lower than the melting-point of pyroxene, but which lies in the region where hornblende is the stable modification.

page 503 note 1 Teall, & Dakyns, , loc. cit., p. 115.Google Scholar

page 503 note 2 Geology of Ben Wyvis, etc. (Mem. Geol. Surv. Scotland), 1912, p. 127.Google Scholar

page 507 note 1 Flett, in Geology of Lizard and Meneage (Mem. Geol. Surv. England), 1912, pp. 36, 46.Google Scholar

page 507 note 2 Flett, in Geology of Seaboard, Mid-Argyll (Mem. Geol. Surv. Scotland), 1909, pp. 47–50.Google Scholar

page 507 note 3 At several other places on Garabal Hill evidence of faulting is found; thus at loc. iv (see Map, Fig. 1) a line of brecciated diorite with numerous quartz-veins can be traced for about 20 yards.

page 507 note 4 Williams, G. H., Bull. U.S. Geol. Surv., 1886, No. 28, p. 31;Google Scholar Chester, F. D., Bull., 1890, No. 58, p. 35.Google Scholar